In the conventional inspection process of a heat flux sensor, a predetermined heat flow is applied to the heat flux sensor and a sensor output is measured, and the heat flux sensor is evaluated for characteristics based on the measurement results. Specifically, the inspection process is carried out based on whether the relationship between the rate of heat flow generated by the application of a predetermined heat flow and the sensor output (for example, output voltage) meets a desired relationship. The method for the characteristic evaluation will be described with reference to FIG. 19.
As illustrated in FIG. 19, according to the conventional method, a rectangular block surrounded by an electrothermal material J2 with favorable thermal conductivity such as copper (Cu) is prepared on the circumferences of heating bodies J1 formed of sheath heaters or the like with insulation coatings on outer surfaces. Then, a heat flux sensor J3 as a measurement target is disposed on the upper surface of the rectangular block. In addition, a cooling unit J4 capable of cooling a material by using a Peltier element or having a coolant flowing therein is disposed opposite to the rectangular block with the heat flux sensor J3 therebetween. The heat flux sensor J3 measures heat flux resulting from heating by the heating bodies J1 and cooling by the cooling unit J4. The inspection process is carried out based on the result of determination on whether the output voltage from the heat flux sensor J3 as the measurement result meets the desired relationship with the heat flow generated by the heating bodies J1.
In the case of using such a rectangular block, heat leaks from the side and bottom surfaces of the rectangular block other than a mounting surface where the heat flux sensor J3 is disposed, and all the heat flow generated by the heating bodies J1 is not transferred to the heat flux sensor J3. Accordingly, the heat flow transferred to the heat flux sensor J3 does not become equal to the heat flow generated by the heating bodies J1. As a result, the relationship between the heat flow generated by the heating bodies J1 and the output voltage from the heat flux sensor J3 does not meet the desired relationship and the inspection process cannot be carried out precisely.
Therefore, according to the conventional method as illustrated in FIG. 19, a heat insulation material J5 is disposed on the side and bottom surfaces of the rectangular block to suppress heat leakage from these surfaces of the rectangular block other than the mounting surface where the heat flux sensor J3 is disposed.